As we look ahead to the next four years, it's not just Congress that will undergo change. Four of the nine Supreme Court justices are over the age of 70, meaning there's a real possibility for at least one new court appointment during President Obama's second term.

The two most likely justices, says NPR legal affairs correspondent Nina Totenberg, are liberal justices Ruth Bader Ginsburg, who is 79, and Stephen Breyer, who is 74.

"If they were replaced by somebody President Obama would pick, it would not change the ideological makeup of the court dramatically," Totenberg tells Guy Raz, host of weekends on All Things Considered.

If one of the two conservative justices over 70, Antonin Scalia and Anthony Kennedy, both 76, were to step down, however, you would likely see an intense battle over the appointment, Totenberg says.

"The court is split on so many issues 5-4, currently with the conservatives dominating," she says.

So who might be on Obama's short list for an appointment? Totenberg says if Ginsburg steps down, she doesn't see the president appointing a male to replace her; this would put the court back to a male-to-female balance of 7-2.

One woman mentioned often, Totenberg says, is California Attorney General Kamala Harris. But Harris also has some political prospects, and possibly a gubernatorial run in her future.

Possibilities for male appointees are Paul Watford, on the Ninth Circuit Court of Appeals, and Sri Srinivasan, who was nominated to the D.C. Court of Appeals, but has yet to be confirmed.

Whether or not any of those justices will step down during Obama's second term no one can know for sure, and the lifetime position of a Supreme Court justice is not something given up lightly, Totenberg says.

"These people love this work ... it's who they are," she says. "So in some ways, they view it as stepping down from their life, and the president's desires often don't come first."

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Transcript

GUY RAZ, HOST:

Now, there has been vigorous public debate this election cycle about the Supreme Court, from the Citizens United case to the ruling on the Affordable Care Act. The court could be headed for a shake-up over the next four years.

Four of the nine justices are over the age of 70. That means there's a real possibility for at least one new court appointment during President Obama's second term. Here to explain what changes we might see is NPR's legal affairs correspondent Nina Totenberg. Hi, Nina.

NINA TOTENBERG, BYLINE: Nice to be here.

RAZ: OK. Let's start with the makeup of the court. Can we expect any of these justices to potentially step down?

TOTENBERG: We have two liberal justices who could conceivably step down. Justice Ginsburg is 79 and Justice Breyer who's 74. And if they were replaced by somebody that President Obama would pick, it would not change the ideological makeup of the court dramatically. On the other hand, two of the conservative justices, Antonin Scalia and Anthony Kennedy, are 76. Now, if one of them were to step down, we would see the most enormous...

RAZ: Dramatic change.

TOTENBERG: ...battle royal over this because the court is split on so many issues, five to four, with currently the conservatives dominating.

RAZ: A lot of this is a parlor game, but, of course, we have to be prepared for the possibility that this could happen. Who is on the bench? I mean, who - when we talk about people who President Obama might consider, who are we looking at?

TOTENBERG: If Justice Ginsburg were to step down, I cannot imagine President Obama naming a male and taking the court back to a...

RAZ: Even though his previous choices have been females.

TOTENBERG: Well, yes, but it would take the court back to a seven-to-two male/female balance. I can't imagine him doing that. It's easier to pick the outstanding men, particularly of color. So Paul Watford on the Ninth Circuit Court of Appeals, said to be very brilliant; he's African-American, would be at the top of the list. Sri Srinivasan, who hasn't been confirmed yet but has been named to the D.C. Circuit and has been in the solicitor general's office for quite a while.

Women are harder. There really aren't those kind of standout names, certainly of color. And Republicans have been very aggressive about stopping some of the women from being confirmed.

RAZ: I mean, Elena Kagan, of course, did not have experience as a judge. She had been solicitor general. What about, you know, people without experience on the bench?

TOTENBERG: Well, the person who gets named most often is Kamala Harris, the current attorney general of California who's African-American. But she also has a lot of political prospects, perhaps to run for governor at some point.

RAZ: Nina, what are the odds that you give that the president will have at least one more Supreme Court appointment to make?

TOTENBERG: Sixty-forty.

RAZ: Sixty-forty. That's pretty good. That's a pretty good shot that it'll happen in the next four years.

TOTENBERG: Or 50-50.

(LAUGHTER)

RAZ: Or 50-50. I got you. OK.

TOTENBERG: You know, I think it's - you cannot imagine. These people love this work. And they don't give it up easily. It's who they are. So in some ways, they view it as stepping down from their life. And the president's desires often don't come first.